The present invention relates in general to the field of recombinant DNA species, and more particularly to the production of chimeric genes.
S-adenosylmethionine is an important metabolic agent that is formed in the body by the reaction of methionine, an essential amino acid, with adenosine triphosphate (ATP). S-adenosylmethionine is active in more than forty biological reactions in vivo. S-adenosylmethionine also operates in association with folic acid and vitamin B-12 as a methylating agent, and is essential for the formation of many sulfur-containing compounds in the body, including glutathione and various components of cartilaginous connective tissue.
The body normally generates the required level of S-adenosylmethionine directly from the amino acid methionine; however, a deficiency of methionine, folic acid, or vitamin B-12 can result in decreased levels of S-adenosylmethionine. There is interest in the effects of supplemental dosages of S-adenosylmethionine on various conditions. The interest in supplementation stems, in part, from findings that the elderly and those suffering from osteoarthritis, various liver problems, and depression typically have lowered levels of S-adenosylmethionine. It is also known that merely increasing the dietary intake of methionine does not result in an increase in the concentration of S-adenosylmethionine in the body. S-adenosylmethionine is now widely distributed as an over-the-counter dietary supplement.
S-adenosylmethionine is primarily used in the treatment of five conditions: depression, osteoarthritis, fibromyalgia, cirrhosis of the liver and migraine headaches. There have been numerous studies that have supported the efficacy of S-adenosylmethionine for the treatment of these conditions. It has also been recognized that S-adenosylmethionine has an excellent safety record, and is therefore appropriate for long-term use by patients.
A major drawback to the use of S-adenosylmethionine as a medicament is the expense. Present methods of production rely on the modification of methionine. Unfortunately, the purified methionine used as a starting material is relatively expensive. There is therefore a need for a method of production of S-adenosylmethionine that eliminates the need to provide a source of methionine.